/*
 * Copyright 2011-2012 Calxeda, Inc.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/err.h>
#include <linux/clk.h>
#include <linux/clk-provider.h>
#include <linux/io.h>
#include <linux/of.h>
#include <linux/of_address.h>

#define HB_PLL_LOCK_500     0x20000000
#define HB_PLL_LOCK     0x10000000
#define HB_PLL_DIVF_SHIFT   20
#define HB_PLL_DIVF_MASK    0x0ff00000
#define HB_PLL_DIVQ_SHIFT   16
#define HB_PLL_DIVQ_MASK    0x00070000
#define HB_PLL_DIVR_SHIFT   8
#define HB_PLL_DIVR_MASK    0x00001f00
#define HB_PLL_RANGE_SHIFT  4
#define HB_PLL_RANGE_MASK   0x00000070
#define HB_PLL_BYPASS       0x00000008
#define HB_PLL_RESET        0x00000004
#define HB_PLL_EXT_BYPASS   0x00000002
#define HB_PLL_EXT_ENA      0x00000001

#define HB_PLL_VCO_MIN_FREQ 2133000000
#define HB_PLL_MAX_FREQ     HB_PLL_VCO_MIN_FREQ
#define HB_PLL_MIN_FREQ     (HB_PLL_VCO_MIN_FREQ / 64)

#define HB_A9_BCLK_DIV_MASK 0x00000006
#define HB_A9_BCLK_DIV_SHIFT    1
#define HB_A9_PCLK_DIV      0x00000001

struct hb_clk {
    struct clk_hw   hw;
    void __iomem    *reg;
    char *parent_name;
};
#define to_hb_clk(p) container_of(p, struct hb_clk, hw)

static int clk_pll_prepare(struct clk_hw *hwclk)
{
    struct hb_clk *hbclk = to_hb_clk(hwclk);
    u32 reg;

    reg = readl(hbclk->reg);
    reg &= ~HB_PLL_RESET;
    writel(reg, hbclk->reg);

    while ((readl(hbclk->reg) & HB_PLL_LOCK) == 0)
        ;
    while ((readl(hbclk->reg) & HB_PLL_LOCK_500) == 0)
        ;

    return 0;
}

static void clk_pll_unprepare(struct clk_hw *hwclk)
{
    struct hb_clk *hbclk = to_hb_clk(hwclk);
    u32 reg;

    reg = readl(hbclk->reg);
    reg |= HB_PLL_RESET;
    writel(reg, hbclk->reg);
}

static int clk_pll_enable(struct clk_hw *hwclk)
{
    struct hb_clk *hbclk = to_hb_clk(hwclk);
    u32 reg;

    reg = readl(hbclk->reg);
    reg |= HB_PLL_EXT_ENA;
    writel(reg, hbclk->reg);

    return 0;
}

static void clk_pll_disable(struct clk_hw *hwclk)
{
    struct hb_clk *hbclk = to_hb_clk(hwclk);
    u32 reg;

    reg = readl(hbclk->reg);
    reg &= ~HB_PLL_EXT_ENA;
    writel(reg, hbclk->reg);
}

static unsigned long clk_pll_recalc_rate(struct clk_hw *hwclk,
        unsigned long parent_rate)
{
    struct hb_clk *hbclk = to_hb_clk(hwclk);
    unsigned long divf, divq, vco_freq, reg;

    reg = readl(hbclk->reg);
    if (reg & HB_PLL_EXT_BYPASS) {
        return parent_rate;
    }

    divf = (reg & HB_PLL_DIVF_MASK) >> HB_PLL_DIVF_SHIFT;
    divq = (reg & HB_PLL_DIVQ_MASK) >> HB_PLL_DIVQ_SHIFT;
    vco_freq = parent_rate * (divf + 1);

    return vco_freq / (1 << divq);
}

static void clk_pll_calc(unsigned long rate, unsigned long ref_freq,
                         u32 *pdivq, u32 *pdivf)
{
    u32 divq, divf;
    unsigned long vco_freq;

    if (rate < HB_PLL_MIN_FREQ) {
        rate = HB_PLL_MIN_FREQ;
    }
    if (rate > HB_PLL_MAX_FREQ) {
        rate = HB_PLL_MAX_FREQ;
    }

    for (divq = 1; divq <= 6; divq++) {
        if ((rate * (1 << divq)) >= HB_PLL_VCO_MIN_FREQ) {
            break;
        }
    }

    vco_freq = rate * (1 << divq);
    divf = (vco_freq + (ref_freq / 2)) / ref_freq;
    divf--;

    *pdivq = divq;
    *pdivf = divf;
}

static long clk_pll_round_rate(struct clk_hw *hwclk, unsigned long rate,
                               unsigned long *parent_rate)
{
    u32 divq, divf;
    unsigned long ref_freq = *parent_rate;

    clk_pll_calc(rate, ref_freq, &divq, &divf);

    return (ref_freq * (divf + 1)) / (1 << divq);
}

static int clk_pll_set_rate(struct clk_hw *hwclk, unsigned long rate,
                            unsigned long parent_rate)
{
    struct hb_clk *hbclk = to_hb_clk(hwclk);
    u32 divq, divf;
    u32 reg;

    clk_pll_calc(rate, parent_rate, &divq, &divf);

    reg = readl(hbclk->reg);
    if (divf != ((reg & HB_PLL_DIVF_MASK) >> HB_PLL_DIVF_SHIFT)) {
        /* Need to re-lock PLL, so put it into bypass mode */
        reg |= HB_PLL_EXT_BYPASS;
        writel(reg | HB_PLL_EXT_BYPASS, hbclk->reg);

        writel(reg | HB_PLL_RESET, hbclk->reg);
        reg &= ~(HB_PLL_DIVF_MASK | HB_PLL_DIVQ_MASK);
        reg |= (divf << HB_PLL_DIVF_SHIFT) | (divq << HB_PLL_DIVQ_SHIFT);
        writel(reg | HB_PLL_RESET, hbclk->reg);
        writel(reg, hbclk->reg);

        while ((readl(hbclk->reg) & HB_PLL_LOCK) == 0)
            ;
        while ((readl(hbclk->reg) & HB_PLL_LOCK_500) == 0)
            ;
        reg |= HB_PLL_EXT_ENA;
        reg &= ~HB_PLL_EXT_BYPASS;
    } else {
        writel(reg | HB_PLL_EXT_BYPASS, hbclk->reg);
        reg &= ~HB_PLL_DIVQ_MASK;
        reg |= divq << HB_PLL_DIVQ_SHIFT;
        writel(reg | HB_PLL_EXT_BYPASS, hbclk->reg);
    }
    writel(reg, hbclk->reg);

    return 0;
}

static const struct clk_ops clk_pll_ops = {
    .prepare = clk_pll_prepare,
    .unprepare = clk_pll_unprepare,
    .enable = clk_pll_enable,
    .disable = clk_pll_disable,
    .recalc_rate = clk_pll_recalc_rate,
    .round_rate = clk_pll_round_rate,
    .set_rate = clk_pll_set_rate,
};

static unsigned long clk_cpu_periphclk_recalc_rate(struct clk_hw *hwclk,
        unsigned long parent_rate)
{
    struct hb_clk *hbclk = to_hb_clk(hwclk);
    u32 div = (readl(hbclk->reg) & HB_A9_PCLK_DIV) ? 8 : 4;
    return parent_rate / div;
}

static const struct clk_ops a9periphclk_ops = {
    .recalc_rate = clk_cpu_periphclk_recalc_rate,
};

static unsigned long clk_cpu_a9bclk_recalc_rate(struct clk_hw *hwclk,
        unsigned long parent_rate)
{
    struct hb_clk *hbclk = to_hb_clk(hwclk);
    u32 div = (readl(hbclk->reg) & HB_A9_BCLK_DIV_MASK) >> HB_A9_BCLK_DIV_SHIFT;

    return parent_rate / (div + 2);
}

static const struct clk_ops a9bclk_ops = {
    .recalc_rate = clk_cpu_a9bclk_recalc_rate,
};

static unsigned long clk_periclk_recalc_rate(struct clk_hw *hwclk,
        unsigned long parent_rate)
{
    struct hb_clk *hbclk = to_hb_clk(hwclk);
    u32 div;

    div = readl(hbclk->reg) & 0x1f;
    div++;
    div *= 2;

    return parent_rate / div;
}

static long clk_periclk_round_rate(struct clk_hw *hwclk, unsigned long rate,
                                   unsigned long *parent_rate)
{
    u32 div;

    div = *parent_rate / rate;
    div++;
    div &= ~0x1;

    return *parent_rate / div;
}

static int clk_periclk_set_rate(struct clk_hw *hwclk, unsigned long rate,
                                unsigned long parent_rate)
{
    struct hb_clk *hbclk = to_hb_clk(hwclk);
    u32 div;

    div = parent_rate / rate;
    if (div & 0x1) {
        return -EINVAL;
    }

    writel(div >> 1, hbclk->reg);
    return 0;
}

static const struct clk_ops periclk_ops = {
    .recalc_rate = clk_periclk_recalc_rate,
    .round_rate = clk_periclk_round_rate,
    .set_rate = clk_periclk_set_rate,
};

static __init struct clk *hb_clk_init(struct device_node *node, const struct clk_ops *ops)
{
    u32 reg;
    struct hb_clk *hb_clk;
    const char *clk_name = node->name;
    const char *parent_name;
    struct clk_init_data init;
    struct device_node *srnp;
    int rc;

    rc = of_property_read_u32(node, "reg", &reg);
    if (WARN_ON(rc)) {
        return NULL;
    }

    hb_clk = kzalloc(sizeof(*hb_clk), GFP_KERNEL);
    if (WARN_ON(!hb_clk)) {
        return NULL;
    }

    /* Map system registers */
    srnp = of_find_compatible_node(NULL, NULL, "calxeda,hb-sregs");
    hb_clk->reg = of_iomap(srnp, 0);
    BUG_ON(!hb_clk->reg);
    hb_clk->reg += reg;

    of_property_read_string(node, "clock-output-names", &clk_name);

    init.name = clk_name;
    init.ops = ops;
    init.flags = 0;
    parent_name = of_clk_get_parent_name(node, 0);
    init.parent_names = &parent_name;
    init.num_parents = 1;

    hb_clk->hw.init = &init;

    rc = clk_hw_register(NULL, &hb_clk->hw);
    if (WARN_ON(rc)) {
        kfree(hb_clk);
        return NULL;
    }
    rc = of_clk_add_hw_provider(node, of_clk_hw_simple_get, &hb_clk->hw);
    return hb_clk->hw.clk;
}

static void __init hb_pll_init(struct device_node *node)
{
    hb_clk_init(node, &clk_pll_ops);
}
CLK_OF_DECLARE(hb_pll, "calxeda,hb-pll-clock", hb_pll_init);

static void __init hb_a9periph_init(struct device_node *node)
{
    hb_clk_init(node, &a9periphclk_ops);
}
CLK_OF_DECLARE(hb_a9periph, "calxeda,hb-a9periph-clock", hb_a9periph_init);

static void __init hb_a9bus_init(struct device_node *node)
{
    struct clk *clk = hb_clk_init(node, &a9bclk_ops);
    clk_prepare_enable(clk);
}
CLK_OF_DECLARE(hb_a9bus, "calxeda,hb-a9bus-clock", hb_a9bus_init);

static void __init hb_emmc_init(struct device_node *node)
{
    hb_clk_init(node, &periclk_ops);
}
CLK_OF_DECLARE(hb_emmc, "calxeda,hb-emmc-clock", hb_emmc_init);
